The Hox cooperativity motif of the chimeric oncoprotein E2a-Pbx1 is necessary and sufficient for oncogenesis

Ching-Pin Chang, Immaculata De Vivo, Michael L. Cleary

Research output: Contribution to journalArticle

58 Citations (Scopus)

Abstract

E2a-Pbx1 chimeric oncoproteins result from fusion of the E2A and PBX1 genes at the sites of t(1;19) chromosomal translocations in a subset acute lymphoblastic leukemias. Experimentally, E2a-Pbx1 transforms a variety of cell types, including fibroblasts, myeloid progenitors, and lymphoblasts. Structure-function studies have shown that contributions from both E2a and Pbx1 are necessary for oncogenesis, but the Pbx1 homeodomain is dispensable and the required portion of Pbx1 has not been delineated. In this study, we used deletional and site-directed mutagenesis to identify portions of Pbx1 necessary for oncogenic and transcriptional activities of E2a-Pbx1. These studies defined a motif (named the Hox cooperativity motif [HCM]) carboxy terminal to the Pbx homeodomain that is required for cooperative DNA binding, cellular transcriptional activity, and the oncogenic potential of E2a-Pbx1. The HCM is highly conserved throughout the Pbx/exd subfamily of divergent homeodomain proteins and functions in DNA-binding assays as a potential contact site for Hox dimerization. E2a-Pbx1 proteins with interstitial deletion or single-point mutations in the HCM could neither activate transcription in cellular assays nor transform NIH 3T3 cells. An E2a-Pbx1 mutant containing 50 amino acids of Pbx1b spanning the HCM but lacking the homeodomain was capable of inducing fibroblast transformation. Thus, the HCM is a necessary and sufficient contribution of Pbx1 for oncogenesis induced by E2a-Pbx1 and accounts for its homeodomain-independent transforming properties. Since subtle alterations of the Pbx HCM result in complete abrogation of transforming activity whereas the homeodomain is entirely dispensable, we conclude that interactions mediated by the HCM are more important for transformation by E2a-Pbx1 than interactions with cognate Pbx DNA sites.

Original languageEnglish (US)
Pages (from-to)81-88
Number of pages8
JournalMolecular and Cellular Biology
Volume17
Issue number1
StatePublished - Jan 1997
Externally publishedYes

Fingerprint

Oncogene Proteins
Carcinogenesis
DNA
Fibroblasts
Homeodomain Proteins
NIH 3T3 Cells
Genetic Translocation
Dimerization
Site-Directed Mutagenesis
Precursor Cell Lymphoblastic Leukemia-Lymphoma
Point Mutation
Amino Acids
Genes
Proteins

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Cell Biology

Cite this

The Hox cooperativity motif of the chimeric oncoprotein E2a-Pbx1 is necessary and sufficient for oncogenesis. / Chang, Ching-Pin; De Vivo, Immaculata; Cleary, Michael L.

In: Molecular and Cellular Biology, Vol. 17, No. 1, 01.1997, p. 81-88.

Research output: Contribution to journalArticle

Chang, Ching-Pin ; De Vivo, Immaculata ; Cleary, Michael L. / The Hox cooperativity motif of the chimeric oncoprotein E2a-Pbx1 is necessary and sufficient for oncogenesis. In: Molecular and Cellular Biology. 1997 ; Vol. 17, No. 1. pp. 81-88.
@article{98eee393b73744809408797755a92bf2,
title = "The Hox cooperativity motif of the chimeric oncoprotein E2a-Pbx1 is necessary and sufficient for oncogenesis",
abstract = "E2a-Pbx1 chimeric oncoproteins result from fusion of the E2A and PBX1 genes at the sites of t(1;19) chromosomal translocations in a subset acute lymphoblastic leukemias. Experimentally, E2a-Pbx1 transforms a variety of cell types, including fibroblasts, myeloid progenitors, and lymphoblasts. Structure-function studies have shown that contributions from both E2a and Pbx1 are necessary for oncogenesis, but the Pbx1 homeodomain is dispensable and the required portion of Pbx1 has not been delineated. In this study, we used deletional and site-directed mutagenesis to identify portions of Pbx1 necessary for oncogenic and transcriptional activities of E2a-Pbx1. These studies defined a motif (named the Hox cooperativity motif [HCM]) carboxy terminal to the Pbx homeodomain that is required for cooperative DNA binding, cellular transcriptional activity, and the oncogenic potential of E2a-Pbx1. The HCM is highly conserved throughout the Pbx/exd subfamily of divergent homeodomain proteins and functions in DNA-binding assays as a potential contact site for Hox dimerization. E2a-Pbx1 proteins with interstitial deletion or single-point mutations in the HCM could neither activate transcription in cellular assays nor transform NIH 3T3 cells. An E2a-Pbx1 mutant containing 50 amino acids of Pbx1b spanning the HCM but lacking the homeodomain was capable of inducing fibroblast transformation. Thus, the HCM is a necessary and sufficient contribution of Pbx1 for oncogenesis induced by E2a-Pbx1 and accounts for its homeodomain-independent transforming properties. Since subtle alterations of the Pbx HCM result in complete abrogation of transforming activity whereas the homeodomain is entirely dispensable, we conclude that interactions mediated by the HCM are more important for transformation by E2a-Pbx1 than interactions with cognate Pbx DNA sites.",
author = "Ching-Pin Chang and {De Vivo}, Immaculata and Cleary, {Michael L.}",
year = "1997",
month = "1",
language = "English (US)",
volume = "17",
pages = "81--88",
journal = "Molecular and Cellular Biology",
issn = "0270-7306",
publisher = "American Society for Microbiology",
number = "1",

}

TY - JOUR

T1 - The Hox cooperativity motif of the chimeric oncoprotein E2a-Pbx1 is necessary and sufficient for oncogenesis

AU - Chang, Ching-Pin

AU - De Vivo, Immaculata

AU - Cleary, Michael L.

PY - 1997/1

Y1 - 1997/1

N2 - E2a-Pbx1 chimeric oncoproteins result from fusion of the E2A and PBX1 genes at the sites of t(1;19) chromosomal translocations in a subset acute lymphoblastic leukemias. Experimentally, E2a-Pbx1 transforms a variety of cell types, including fibroblasts, myeloid progenitors, and lymphoblasts. Structure-function studies have shown that contributions from both E2a and Pbx1 are necessary for oncogenesis, but the Pbx1 homeodomain is dispensable and the required portion of Pbx1 has not been delineated. In this study, we used deletional and site-directed mutagenesis to identify portions of Pbx1 necessary for oncogenic and transcriptional activities of E2a-Pbx1. These studies defined a motif (named the Hox cooperativity motif [HCM]) carboxy terminal to the Pbx homeodomain that is required for cooperative DNA binding, cellular transcriptional activity, and the oncogenic potential of E2a-Pbx1. The HCM is highly conserved throughout the Pbx/exd subfamily of divergent homeodomain proteins and functions in DNA-binding assays as a potential contact site for Hox dimerization. E2a-Pbx1 proteins with interstitial deletion or single-point mutations in the HCM could neither activate transcription in cellular assays nor transform NIH 3T3 cells. An E2a-Pbx1 mutant containing 50 amino acids of Pbx1b spanning the HCM but lacking the homeodomain was capable of inducing fibroblast transformation. Thus, the HCM is a necessary and sufficient contribution of Pbx1 for oncogenesis induced by E2a-Pbx1 and accounts for its homeodomain-independent transforming properties. Since subtle alterations of the Pbx HCM result in complete abrogation of transforming activity whereas the homeodomain is entirely dispensable, we conclude that interactions mediated by the HCM are more important for transformation by E2a-Pbx1 than interactions with cognate Pbx DNA sites.

AB - E2a-Pbx1 chimeric oncoproteins result from fusion of the E2A and PBX1 genes at the sites of t(1;19) chromosomal translocations in a subset acute lymphoblastic leukemias. Experimentally, E2a-Pbx1 transforms a variety of cell types, including fibroblasts, myeloid progenitors, and lymphoblasts. Structure-function studies have shown that contributions from both E2a and Pbx1 are necessary for oncogenesis, but the Pbx1 homeodomain is dispensable and the required portion of Pbx1 has not been delineated. In this study, we used deletional and site-directed mutagenesis to identify portions of Pbx1 necessary for oncogenic and transcriptional activities of E2a-Pbx1. These studies defined a motif (named the Hox cooperativity motif [HCM]) carboxy terminal to the Pbx homeodomain that is required for cooperative DNA binding, cellular transcriptional activity, and the oncogenic potential of E2a-Pbx1. The HCM is highly conserved throughout the Pbx/exd subfamily of divergent homeodomain proteins and functions in DNA-binding assays as a potential contact site for Hox dimerization. E2a-Pbx1 proteins with interstitial deletion or single-point mutations in the HCM could neither activate transcription in cellular assays nor transform NIH 3T3 cells. An E2a-Pbx1 mutant containing 50 amino acids of Pbx1b spanning the HCM but lacking the homeodomain was capable of inducing fibroblast transformation. Thus, the HCM is a necessary and sufficient contribution of Pbx1 for oncogenesis induced by E2a-Pbx1 and accounts for its homeodomain-independent transforming properties. Since subtle alterations of the Pbx HCM result in complete abrogation of transforming activity whereas the homeodomain is entirely dispensable, we conclude that interactions mediated by the HCM are more important for transformation by E2a-Pbx1 than interactions with cognate Pbx DNA sites.

UR - http://www.scopus.com/inward/record.url?scp=0031031879&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0031031879&partnerID=8YFLogxK

M3 - Article

VL - 17

SP - 81

EP - 88

JO - Molecular and Cellular Biology

JF - Molecular and Cellular Biology

SN - 0270-7306

IS - 1

ER -